Fabricate, characterize, package, and distribute 25,000 sheets and 1,500 tubes of low-density polyethylene for use as primary reference materials for studies of blood materials interactions. The sheets will measure 2.54 X 7.62 X 0.0254 cm. The tubes will have an outside diameter no greater than 5 mm. and an inside diameter no smaller than 4 mm. The characterized samples will be packaged and sterilized in a way determined in consultation with the Project Officer. They will be placed in a heat-sealed plactic bag with a data/instruction sheet and user questionnaire.